1. Field of the Invention
This invention relates to a method of and apparatus for recording surface irregularities of an object in the form of contour lines, and more particularly to a method of and apparatus for recording minute surface irregularities of a moving object such as travelling flexible web-like material by use of a moire effect.
2. Description of the Prior Art
It has been known in the art to record surface irregularities of an object by use of a moire effect. One example of such a method is disclosed in Japanese Patent Public Disclosure No. 49-69160/1974. In this kind of method, there has been a problem that the vertical vibration or movement of the object is recorded together with the surface irregularities as a noise. In case that the object is a flexible web travelling in one direction as a film base handled in a film manufacturing plant, the flexible web is liable to vibrate or flap up and down. Even in case of a rigid material, the vibration thereof makes a noise in the measurement of the surface irregularities.